Field Of the Invention
The present invention relates generally to automatically closing display doors for display cases and the like, and more particularly to an improved door closure mechanism and a related method for use therewith which allows the amount of door closing preloading bias to be easily and quickly adjusted with a high degree of precision to vary the amount of force used to close a display door.
Display cases having display doors containing windows therein are widely used, particularly for applications such as in supermarkets to display refrigerated and frozen foods. The display doors function to retain the cold air within the display cases, thereby conserving energy and reducing operating costs while also efficiently keeping the foods contained therein cold. Since it is common for consumers or their children to forget to securely close the display doors, most such display doors include a closing mechanism therein.
Such closing mechanisms must typically be adjusted when the display doors are first installed, and also at periodic intervals over time to compensate for changes in operating condition such as increased friction, the buildup of dirt, or the loss of elasticity in the element used to bias the display doors from an open position to the closed position. Accordingly, in better quality display doors an adjustment mechanism is included.
One such closing mechanism uses an adjustment mechanism which is located at the bottom of the display door, and which is accessible from the outside of the display case. A cylindrical display pivot element is carried on the bottom of the display door, and is received in a door closer base member mounted on top of the bottom frame member of the display case in which the display door is mounted. The cylindrical display pivot element has a plurality of radially oriented apertures evenly spaced around the outer periphery thereof.
The portion of the cylindrical display pivot element having the plurality of radially extending apertures located therein is received within the door closer base member. The door closer base member has an aperture in the front side thereof which aperture is sufficiently wide to allow access to two adjacent ones of the plurality of radially extending apertures located in the cylindrical display pivot element when the cylindrical display pivot element is received in the door closer base member. By using a pair of pins placed sequentially in the apertures in the cylindrical display pivot element, the cylindrical display pivot element can be rotated to increase or decrease the bias which will be exerted by the biasing member used to close the display door.
When the rotational position of the cylindrical display pivot element with respect to the door closer base member has been made to properly adjust the biasing member, a set pin may be placed in one of the apertures in the cylindrical display pivot element to prevent it from rotating further with respect to the door closer base member. It will be appreciated by those skilled in the art that this adjustment mechanism represents something less than perfection in mechanical design. In addition to being difficult to adjust, this mechanism is also susceptible to total failure whenever the set pin works its way out of the cylindrical display pivot element, leaving the display door closing mechanism totally inoperative.
It is accordingly the primary objective of the present invention that it provide an improved adjustment mechanism for adjusting the bias which will be exerted by the biasing member used to close the display door. As such, the improved door closer adjustment mechanism of the present invention should be improved in two aspects. First, the improved door closer adjustment mechanism of the present invention should be easier to adjust than previously known door closer mechanisms, allowing a user to easily and precisely adjust the degree of bias which will be exerted by the biasing member used to close the display door. Second, the improved door closer adjustment mechanism should positively and surely retain the precise adjustment setting over a period of time, and should not be susceptible to the failure mode exhibited by previously known door closer mechanisms.
In addition, it is a further objective of the present invention that the improved door closer mechanism be small in size, not requiring any more space to install than do previously known door closer mechanisms. It is yet another objective of the improved door closer adjustment mechanism of the present invention that it be usable to replace existing door closure mechanisms without requiring either replacement or extensive modification of existing display doors. It is also an objective of the improved door closer mechanism that a single mechanism be usable on either a display door with its pivot point on the right side or a display door with its pivot point on the left side.
The improved door closer mechanism of the present invention must also be of construction which is both durable and long lasting, and it should require little or no maintenance to be provided by the user. In order to enhance the market appeal of the improved door closer mechanism of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives of the present invention be achieved without incurring any substantial relative disadvantage.